Frame relay devices use a high performance, packet-switched Wide Area Network (WAN) protocol that operates at the data and physical link layers of the OSI reference model. Network carriers or private telecommunications service providers typically operate frame relay networks, and lease frame relay lines to client companies and organizations.

Figure 1: Frame relay overview

You can quickly tell which routers in an AutoDiscovery network diagram are frame relay devices by viewing their properties. Then you can list or edit data link connection identifiers (DLCIs) and frame relay circuits, and change the committed information rate (CIR) values. You can also generate a Permanent Virtual Circuit (PVC) Summary report that lists information about the capacity of a specific frame relay circuit and the frame relay circuit endpoints. The following sections describe how to do each of these things.

Discovering Frame Relay Devices

AutoDiscovery discovers frame relay routers during the normal Layer 3 discovery process. Using the Discovery Wizard, you specify which networks and devices to discover. The discovered devices are placed in the AutoDiscovery database. You can use the Database Viewer to view the contents of the database and the device properties.

To open the Database Viewer, on the AutoDiscovery menu, point to Database Viewer, and then click Open/Close. Or, click the Database Viewer button on the AutoDiscovery and Layout toolbar.

Add frame relay devices to a diagram as you would any other device. Either drag them from the Database Viewer, or use the Add Devices command.

Viewing Frame Relay Device Properties

Right-click a frame relay device on the diagram, and then click Properties on the shortcut menu to display the Network Shape Properties dialog box. The frame relay tab displays the DLCI and CIR values for each interface connected to the selected router.

Creating Frame Relay circuits

Although AutoDiscovery and Layout can discover frame relay devices and their properties, it cannot determine a full circuit, or pairing of PVC's. It discovers all the frame relay devices and interfaces, but needs your input to connect them. To specify the "other end" of the frame relay circuit, right-click a frame relay router and click Create Circuits on the shortcut menu. The DLCI's contained in the selected router appear, along with the other frame relay routers. Simply click the endpoint for the selected DLCI.

Figure 2: Circuit listing

Changing Frame Relay Circuit values

If the frame relay circuit values change, or if you make a mistake when creating circuits, you can easily change their values by right-clicking a device and clicking Edit Circuits on the shortcut menu. You can change endpoint DLCI values, circuit names, and the Committed Information Rate (CIR) link speed for each endpoint.

Changing the Committed Information Rate (CIR)

The CIR is the minimum guaranteed transmission speed between computers in frame relay networks. The CIR value for a virtual circuit is stored in the frame relay Management Information Base (MIB) and is usually set to zero.

To set the CIR for your frame relay network, right-click a frame relay router and click Edit DLCIs on the shortcut menu. Here, you can select a frame relay router and create or change the CIR values for each of the interfaces on the router.

Listing Data Link Connection Identifiers (DLCIs)

A data link connection identifier (DLCI) is a number assigned to a Permanent Virtual Circuit (PVC) endpoint in a frame relay network. Frame relay circuits logically link two DLCIs, and each DLCI of a pair uniquely identifies a PVC endpoint within a local access channel of a frame relay network.

For example, a DLCI value is unique to a single frame relay virtual circuit between two DTE (data terminal equipment) devices, but may not be unique across the whole frame relay network.

You can list the DLCIs that are connected to a selected device. To list DLCI's, right-click a frame relay router on the diagram, and click List DLCIs on the shortcut menu.

AutoDiscovery can automatically connect DLCI endpoints, but it can't automatically associate both endpoints of each DLCI circuit. You must specify the other endpoint of each DLCI.

Generating a Permanent Virtual Circuit (PVC) Summary Report

You can generate a frame relay Permanent Virtual Circuit (PVC) Summary report that lists all frame relay circuits found in the database, including information on the capacity of each specific frame relay circuit, and circuit endpoints.

To create a PVC Summary report, on the AutoDiscovery menu, point to Network Reporting and then click Report Wizard. Or, click the Network Reporting Wizard button on the AutoDiscovery and Layout toolbar. In the Network Reporting Wizard, select the All shapes in the database option, and then select the PVC Summary Report.

The table below shows the types of information the report includes.

PVC Summary Report

Field

Description

Source

The source device connected to the circuit.

Port

The physical port name connected to the source circuit.

DLCI

The data-link connection identifier (DLCI) for the source circuit.

CIR

The committed information rate (CIR) for the circuit Unknown is displayed if a CIR value is not set.

Destination

The destination device connected to the circuit.

Port

The port for the destination circuit.

DLCI

The DLCI for the destination circuit.

Circuit Name

The name of the circuit, which is created automatically. You can rename it in the Edit DLCI dialog box.